Kahweofuran (compound name: 2,3-dihydro-6-methylthieno[2,3-c]furan) is a compound that was isolated by M. Stoll et al. in 1963 as a characteristic aroma component that is present in coffee (Non-Patent Document 1). Its structure was determined by G. Buchi et al. By them, that is to say, the compound was found to have the structure represented by the following formula, and was named kahweofuran (Non-Patent Document 2).

As processes for synthesizing kahweofuran, the process of G. Buchi et al. (Non-Patent Document 2), the process of E. Brenna et al. (Non-Patent Documents 3 and 4), and the process of D. Rewicki et al. (Non-Patent Document 5), are known, but none of them can be said to be efficient. Specifically, the process of G. Buchi et al., which synthesizes kahweofuran in three steps using 4,5-dihydrothiophene-3(2H)-one as a raw material, has problems in that the yield of the Claisen reaction in the first step is low and that two kinds of products are produced in the Grignard reaction in the second step. The process of E. Brenna et al. involves as many as ten steps to produce the compound from the starting material. The process of D. Rewicki et al., although providing a total yield of 12%, has a problem in that it is difficult to obtain 3,4-dibromofuran, which is used as the starting material in the process. Thus, the known synthesis processes cannot be said to be efficient, and have problems when applied to industrial mass-production.
Non-Patent Document 1: Helv. Chim. Acta, 50, 628, (1967)
Non-Patent Document 2: J. Org. Chem., 36, 199, (1971)
Non-Patent Document 3: J. Chem. Research (S), 74, (1998)
Non-Patent Document 4: J. Chem. Research (M), 551, (1998)
Non-Patent Document 5: Liebigs Ann. Chem., 625, (1986)